2002-05-13_PERMIT FILE - C1981041 (3)

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As has been described earlier in this report, a slope stability • study was performed for the proposed storage pile configuration as provided to ROCKY MOUNTAIN GEOTECHNICAL. The results of slope stabil- ity analysis indicated a minimum factor of safety for the most critical slope on the proposed storage pile of 2.302. This value is substan- d ally in excess of the 1.5 minimum fuetcr of safety value, and thus the slope configuration would be considered as stable. Upon completion of our original analysis for the proposed storage pile, additional slope stability analysis was performed in order to determine tY~e combination of slope height and slope angle which would yield the maximum storage for this pile. This analysis resulted in a pile configuration having 2:1 side slopes, with 10-f t. horizontal benches or terraces being located at 30-ft. vertical spacing. This • results in an overall slope angle for the pile of 2.3:1. The most critical slope in this configuration will have a factor of safety of about 1.74. Under this configuration the pile will have a maximum elevation o` approximately 5025 based upon mean cross-section and plan showing pile contours is report on Plate No. 2. This pile configuration rate storage capacity of 2,240,000 cubic yards. increase of approximately 740,000 cubic yards f figuration. sea level datum. A included with this will have an approxi- This represents an rom the original con- The fill material placed in the pile should be compacted to a minimum dry density of 80 pcf in order to achieve a shear strength equal to, or greater tt.an that used in the analysis. This can prob- . ably be accomplished using lifts not exceeding 2-f t. in thickness, which are compacted by tracking or wheel rolling. We would recommend that test strips be made at commencement of waste pile filling